Help!! Having a frustrating time with my 850 hybrid gearbox. Dropped rebuilt motor and box into car in November. All seemed fine but could not select reverse. With Christmas etc I have only just gotten around to investigating it properly this weekend. The box is a hybrid built out of a four synchro gearbox fitted with a matched 850 diff tail to retain the magic wand gear shifter. The box was built for me by a competent mechanic, but did sit around (sealed up) for a long time before being used (eg 15 years probably).

The box selects all four forward gears nicely. In fact it is a sweet, positive change. The shifter will move across to the reverse gate but then it is impossible to pull the lever down to select reverse.

I have checked the reverse detent plunger on the front of the box. That seemed fine. This weekend I stripped off the inlet manifold and exhaust system to get at the linkages on the back of the box. I did realise after toiling in a 35 degree shed for half a day that the knuckle linkage had been fitted back to front (not by me). However, refitting it correctly and carefully indexing each part onto the respective splined shaft has made no difference. All four forward gears - no reverse.

I am now already pretty much resigned to having to pull the entire power unit back out and splitting the motor and box to diagnose what is going on. The problem clearly seems to be in the box, which of course points to the reverse selector detents etc in the very bottom. However, if anyone reading this has any other bright ideas first, I am all ears?

Tartanred

Is the selector (going into box) actually going down to reverse gate section?

Yep Peter, the selector goes down into the reverse gate fine. I can push it down with firm hand pressure. However, no amount of leverage will get the selector rod to turn to engage reverse. Clearly something is not right inside - unless someone can offer me a miraculous solution.